Such continuous conveyors have long been known. In the upper run, workpieces placed on the rotating pallets—also known as workpiece carriers—are transported from one location to another. The workpieces comprise, for example, mounting parts for motor vehicle production that are transported to an assembly line by means of pallets. On the assembly line, the workpieces are removed, for example, by a robot, and are processed by production machines. Generally stated, such continuous conveyors are provided at various points and for the most diverse applications.
The tension elements are often designed as endless transport chains that rotate in the two side sections of the continuous conveyor. They are driven by motor-driven sprockets, which are arranged in the two reversal sections. With a known continuous conveyor, which is described in WO 2004/000698 A1, a gear wheel coupled with a hysteresis clutch or a viscose clutch is provided on each side of a pallet. The two gear wheels engage in the respective transport chain in the corresponding side section. The gear wheel does not rotate when the pallet is unimpeded; rather, it acts as a rigid pin that carries the pallet. Only when there is an obstacle to the continuation, in particular a waiting pallet, do the two gear wheels rotate in the continuously further driven transport chain, until the resistance by the preceding pallet no longer exists. So that the pallet can also be driven by means of the gear wheels in reversal sections, with this known device, each of the transport chains is formed with two rows or two tiers (or even three tiers), whereas such two rows are rigidly coupled with each other. Each of the transport chains is driven by a sprocket, whereas this sprocket engages only in one or, in the case of a three-tier formation, two strands of the chain, such that one chain strand remains free. The respective gear wheel of the pallet, which is connected to the hysteresis or viscose clutch, then runs in this chain strand, such that it is constantly in engagement with this series of transport chains.
The known pallet also features a running roller or a running wheel on its underside in all four corners, whereas such rollers run in or on rails along the two paths, which forcibly guide the running rollers and thus secure the pallet. Furthermore, a latch is fastened below each pallet, which is arranged opposite to one of the specified toothed rims. This latch forms a form closure with the chain in the reversal section, by which a secure travel of the pallet in the reversal section is ensured. However, with this structure, a simple lifting of the pallet by an operator is not possible.
Additional structures are known from the state of the art, which describe solutions for the deflection of pallets in the reversal sections from the upper run to the lower run. With known arrangements, a synchronization (for example) of engagement means arranged on the pallet and correspondingly formed carrying means on the tension elements is required, the drive of which is controlled by signals from light barriers. However, a deflection without an interruption in the travel of the pallet is preferred. A solution to this effect is shown, for example, in DE 10 2009 056 545 A1, in which a design with a planetary gear transmission is described. However, such structures are relatively complex.
Therefore, the task of the present invention to provide a secure and cost-effective solution for the deflection of a pallet for its transfer from the upper run to the lower run and vice versa.